DFW Heronries - City of Carrollton, TX

Transcription

DFW Heronries - City of Carrollton, TX
DFW Heronries
Brett Johnson
Urban Wildlife Biologist
Texas Parks and Wildlife Dept.
Today’s Topics
Species of Interest
Protection Issues
Early Detection
Deterrent Methods
Habitat Modification
Today’s Topics
Species of Interest
Protection Issues
Early Detection
Deterrent Methods
Habitat Modification
Cattle Egret
Historically native to parts of
Asia, Africa and Europe
Extremely fast range expansion
Seem to follow spread of cattle
―Empty Niche‖ - no real
competition
1st Appear - 1941
1st US breeding – 1953
Most abundant species in
heronries
Cattle Egret
Protected under the MBTA
―The Cattle Egret got here by
means of a natural range
expansion. They were not
intentionally introduced or
accidently released. They
followed the increase of cattle
production worldwide and have
long range migration. They also
pose no immediate threat to
―native‖ species. So they ARE
legally covered under the MBTA.‖
USFWS Wildlife Biologist
Cattle Egret
Bill — yellow to orange
Short, thick neck
Hunched posture
Yellowish legs
Fly in ―V‖ pattern formation
Breed - Late April-October
Little Blue Heron
Typically 2nd most
abundant*
Dark slate-blue body
Maroon-brown head,
neck
Legs blue-green
Breeding season
extends from late
March to late July
Snowy Egret
3rd Most Common
Bill is thin, long and black
Black legs
Bright yellow feet
Long, slender neck
Breeding season extends
usually from late March to
early August
Great Egret
Big, white bird
Bill is long and yellow
Legs and feet are black
# in heronry varies widely
Breeding season
extends from early
March to early August
Today’s Topics
Species of Interest
Protection Issues
Early Detection
Deterrent Methods
Habitat Modification
Migratory Bird Treaty Act of 1918
• This 1918 Act implemented the 1916 convention
between the United States and Great Britain (for
Canada)
• Similar conventions between the United States and
Mexico (1936), Japan (1972) and the Union of Soviet
Socialists Republics (1976)
• Each new treaty has been incorporated into the
MBTA as an amendment and the provisions of the
new treaty are implemented domestically
• Established Federal responsibilities for the
protection of nearly all species of birds, their eggs
and nests
• 836 species are legally protected, 58 legally hunted
MBTA Protection
• Made it illegal for people to "take"
migratory birds, their eggs, feathers or
nests
• Take is defined in the MBTA to include
by any means or in any manner (even
unintentional), any attempt at hunting,
pursuing, wounding, killing,
possessing or transporting any
migratory bird, nest, egg or part
thereof
What can and cannot be
done legally?
“Simply put, it is prohibited to kill
the birds or harass them in any way
that would cause the abandonment
and death of eggs or
hatchlings. Anything short of this is
not a violation of the MBTA.”
USFWS Wildlife Biologist
What is the difference between
roosting and nesting?
―Birds don't typically sit on a nest
when roosting outside the nesting
season. Almost anything can be
done to drive them away when
they are only roosting.‖
USFWS Wildlife Biologist
When is it too late to harass
the birds?
―The window of opportunity is
fairly short, from the time the
birds first arrive until an egg is
laid in a nest.‖
USFWS Wildlife Biologist
What about destroying nests
BEFORE nesting?
“A newly built nest can be destroyed
up until the moment an egg is
laid. After that, it may be removed only
after the nest is no longer used by the
parent birds rearing offspring.”
End of nesting season
nest removal
“In cases where a colony is no longer
active (i.e. no evidence of the colonial
species using the colony site for nesting
purposes in the current year), then those
old nests may be destroyed at any time
without the need for a permit.”
Interim Empty Nest Policy of the U. S. Fish and Wildlife Service, Region 2
―Take of nests in
partially or fully active
colonies must be done
by trained, permitted
Wildlife Services
personnel‖
Interim Empty Nest Policy of the U. S. Fish and Wildlife Service, Region 2
―Active or Partially Active Colonies. Once egg
laying has commenced by any of those
birds, all nest destruction must cease.
Destruction of empty nests in an active or
partially active colony will likely threaten
surrounding nests that contain eggs or
nestlings; therefore it will not be allowed except
on a case-by-case basis as
determined by the Migratory Bird Permits
Office.‖
Interim Empty Nest Policy of the U. S. Fish and Wildlife Service, Region 2
―Nest destruction may resume
at the end of the nesting season without a permit
only after all nesting activities
by all birds in the colony have ceased, which should
be by October 1 (i.e. after all
nestlings have fledged and left the site and no eggs
are being incubated by late
nesters). At such time nests containing
infertile/abandoned/dead eggs or long-dead
nestlings may also be destroyed without permit.‖
Interim Empty Nest Policy of the U. S. Fish and Wildlife Service, Region 2
If the window on harassment is
missed and the first egg is in the
nest:
“Permits to take active nests (containing eggs or
nestlings) of colonial species for Depredation
Control purposes will not be issued by the
Migratory Bird Permits Office. Destruction
of such active nests must be done
by trained personnel of the
U.S.D.A. - Wildlife Services.”
Today’s Topics
Species of Interest
Protection Issues
Early Detection
Deterrent Methods
Habitat Modification
―The best way to prevent the
establishment of a heronry is
through public awareness and early
detection. If detected early when the
birds first move in, they are nervous
and can be easily moved with
various scaring methods‖
NUISANCE HERONRIES IN TEXAS:
CHARACTERISTICS AND MANAGEMENT
— Second Edition —
―Municipal administrators should consider
providing training information on heronry
characteristics and initiation to city
police, maintenance personnel and
interested volunteers. A comprehensive
vigil during the early spring could avert
later undesirable circumstances for both
people and birds.‖
NUISANCE HERONRIES IN TEXAS:
CHARACTERISTICS AND MANAGEMENT
— Second Edition —
Today’s Topics
Species of Interest
Protection Issues
Early Detection
Deterrent Methods
Habitat Modification
―Scaring devices such as pyrotechnics
(screamers, badgers), cracker shells (shot from a
12-gauge shotgun), rope-firecrackers and propane
cannons all work effectively‖
To be most effective, combine several of
these methods so that the birds do not
become accustomed to them.
Scare-eye type balloons
have been effective with
SENTRY birds
Today’s Topics
Species of Interest
Protection Issues
Early Detection
Deterrent Methods
Habitat Modification
―Dramatic changes are not
necessary. Such modifications of
a potential nesting area usually
produce longer lasting prevention
than other deterrent methods.‖
Spacing between tree canopies
Open canopies
Egrets LIKE >75% canopy closure
Today’s Topics
Species of Interest
Protection Issues
Early Detection
Deterrent Methods
Habitat Modification
Success depends on your
participation:
• If your trees have nests, remove them
now
• Consider thinning tree canopy
• Use visual deterrents
• If you noticed sentry birds, report this
activity immediately
• Consider helping your neighbor
Questions will be addressed by
panel at the end of the workshop
Brett Johnson
Urban Wildlife Biologist
Texas Parks and Wildlife Deparment
972-293-3841
dallasbiologist@airmail.net